Nature and Science 2017;15(11) http://www.sciencepub.net/nature 69 Effect of Ribavirin on the Testes of Adult Albino Rats (Light Microscopic Study) Mohamed Abdel Hay Autifi, Elsayed Ahmed Abou Salem, Elsayed Abdel Rhman Abdel Hady And Amr Mohamed Younis Medical Anatomy & Embryology Department – Faculty of Medicine – Al-Azhar University Abstract: Background: Ribavirin is one of the approved antiviral drugs indicated for various viral infections. So it is used as a current therapy with interferon alpha for treatment of viral hepatitis C that affects 200 million patients worldwide. This treatment regimen is poorly tolerated because of its side effects and toxicity. The testis is a complex organ concerned with the production of sperms to fertilize the ova and secretion of androgen to maintain the secondary sexual characters and proper spermatogenesis. Objective: The present study was performed to assess ribavirin toxicity on the structure of testicular tissue of adult male rats after exposure to thedrugfor different periods as well as to evaluate the extent of improvement of testiculartissue structure after cessation of drug administration. Results & Conclusion: ribavirin administration produced toxicity and mutagenicity leading to marked serious histological changes of the testis including the spermatogenic cells, sperms, Sertoli cells and Leydig cells. These testicular changes persisted after cessation of ribavirin administration indicating the cumulative toxic effects of ribavirin that caused hypospermatogenesis, oligospermia and then hypospermia. Because it is used nowadays on a large scale allover the world especially in middle aged males (30- 50 years), these serious complications on testicular structure should be considered when physicians prescribe ribavirin in the protocol of viral hepatitis C management. [Mohamed Abdel Hay Autifi, Elsayed Ahmed Abou Salem, Elsayed Abdel Rhman Abdel Hady And Amr Mohamed Younis . Effect of Ribavirin on the Testes of Adult Albino Rats (Light Microscopic Study). Nat Sci 2017;15(11):69-77]. ISSN 1545-0740 (print); ISSN 2375-7167 (online). http://www.sciencepub.net/nature . 9. doi:10.7537/marsnsj151117.09 . ： Keywords Effect; Ribavirin; Testes; Adult; Albino; Rat; (Light Microscopic Study 1. Introduction Hepatitis is a major public health problem worldwide, responsible for considerable morbidity and mortality from liver disease (Lavanchy, 2011). Common causes of hepatitis include viral infection, side effects of certain prescribed drugs and over doses of the drugs (Jihan et al., 2013). Until 2011, the combination of pegylated interferon (PegIFNalph) and Ribavirin for 24 or 48 weeks was the approved treatment for chronic hepatitis C (European Association for the Study of the Liver) (EASL, 2011). Ribavirin is a non specific antiviral drug. It was synthesized in 1970. The broad spectrum antiviral activity was reported in 1972, the aerosolic form was approved for the treatment of respiratory syncytial virus in children (Trevors et al., 2010). The oral ribavirin and interferon alpha (injections) combination therapy was approved by United States Regulatory Authorities in 1998 for the treatment of hepatitis C infection (Lau et al., 2002). The chemical name of ribavirin is 1 beta D ribofurnosy l-1H-1, 2, 4-triazole-3-carboxamide. It is a purine (guanosine) nucleoside analog with modified base and d-ribose sugar, both are necessary for its antiviral activity. Ribavirin has three metabolites mono-, di- and triphosphates that are effective against various RNA and DNA viruses. Ribavirin-5’ – triphosphate is the principal intracellular form (Acosta and Flexner, 2011). Ribavirin exerts its cytotoxicity in the testes after intra peritoneal administration by getting absorbed from peritoneal cavity and reaching to the germ cells. It acts a germ cell mutagen in rats (El Brashy et al., 2007). Weiss et al. (1993) reported that ribavirin administration in cats resulted in pathological changes including hepatocellular vacuolization and centrilobular necrosis. Ribavirin is reversibly cytotoxic to germ cells and decreases the production of sperms (Rao et al., 2002). A decrease in sperm count in a dose and time dependent pattern in the epididymis of rats receiving ribavirin, and its mutagenic agent to germ cells in a transient fashion inducing anomalies of head and tail of sperms (Narayana et al., 2002). In humans, ribavirin was found reversibly genotoxic due to its toxic metabolites in patients of Crimean Congao hemorrhagic fever treated with the therapeutic doses of the drug (Tatar et al., 2009). 2. Material and Methods This study was carried out on 100 male adult albino Wistar rats (weight 200- 250 gm). They were